Integrated system for assessing wound exudates

ABSTRACT

An integrated system for assessing wound exudates from the wound of a patient is described. The system may contain functionality to detect, process and report various wound parameters. The system also may make treatment determinations based on these findings. The system may detect one or more physiological values of the wound exudates from the wound of the patient. The system may means for comparing the one or more detected physiological values to predetermined physiological values in order to obtain a comparison result in real time. The system may include a processor  15  which provides an electronic signal based on a comparison result in which the electronic signal may correspond to guidelines for treating the wound  13 . The system may be integrated with other wound treatment devices, such as negative pressure wound therapy devices (NPWT)  9.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S.Provisional Patent Application No. 61/421,003 filed Dec. 8, 2010, thedisclosure of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

There is a need to autonomously monitor and assess the negative pressurewound therapy (“NPWT”) process and to provide a mechanism to interruptthe NPWT therapy in cases where a contraindication develops in thepatient during use. There is also a further need to improve upon certainfeatures of NPWT devices, such as safety, functionality and intelligent,real time feedback.

Current treatment protocols for assessing wound state involve thequalitative analysis by caregivers. Often, a caregiver may assess thecondition of a wound by the way it looks or smells or the overallappearance of the exudates. Many times, however, the caregiver may notbe assessing the wound regularly or quantitatively. Such assessment mayonly occur at daily or weekly intervals, for example. A disadvantage tothis treatment protocol is that the assessment is of old exudates. Thephysiological parameters of these exudates may change over time, whencompared to their original state in the wound. Color, microbes, oxygen,and temperature all change over time, so the assessment of the exudatesat a time after they have been collected is not an accurate or reliableprediction of wound condition. Additionally, the flow of exudates may bea useful tool in wound assessment. Prior assessment techniques may notoffer a viable solution for monitoring wound exudates flow.

SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a system for assessingwound exudate from the wound of a patient may include a systemcomprising a wound treatment device, detecting means for detecting oneor more values of one or more physiological parameters of the woundexudate, analyzing means for analyzing the values of the one or morephysiological parameters so as to obtain an assessment of the woundexudate, and providing means for providing treatment guidelines based onthe assessment, in which the wound treatment device, the detectingmeans, the analyzing means, and the providing means are integrated.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram representing components of a woundexudate system, in accordance with an embodiment of the presentinvention.

FIG. 2 shows an embodiment of a wound exudate system integrated withinan NPWT device, in accordance with an embodiment of the presentinvention.

FIG. 3 is flow diagram of a wound assessment process, in accordance withan embodiment of the present invention.

FIG. 4 depicts a cross-sectional view of a wound exudate system, inaccordance with an embodiment of the present invention

FIG. 5 depicts an embodiment of a wound exudate system containingmultiple light sources and multiple detectors, in accordance with anembodiment of the present invention.

FIG. 6 depicts a wound exudate system that contains a flow disruptionelement, in accordance with an embodiment of the present invention.

FIG. 7 depicts a wound exudate system containing an inflow feature witha biomarker coating, in accordance with an embodiment of the presentinvention.

FIG. 8 depicts a wound drain tube configured with a tortuous path, inaccordance with an embodiment of the present invention.

FIGS. 9 and 10 depict embodiments of a wound exudate system for pinchinga wound drainage line, in accordance with an embodiment of the presentinvention.

FIG. 11 depicts a wound exudate system with multiple actuators forpinching a wound drain line, in accordance with an embodiment of thepresent invention.

FIG. 12 depicts an alternative embodiment of a wound exudate systemhaving multiple pinching mechanisms disposed along opposing sides of awound drain line, in accordance with an embodiment of the presentinvention.

FIGS. 13 and 14 depict an alternate embodiment of a wound exudate systemcontaining a spring loaded latch in a secured state and released state,respectively, in accordance with an embodiment of the present invention.

FIGS. 15 and 16 depict a wound exudate system configured with aresistive heat break element in a not applied state and an appliedstate, respectively, in accordance with an embodiment of the presentinvention.

FIG. 17 depicts an embodiment of a wound exudate system containing thinmembranes with pressure sensors disposed thereon, in accordance with anembodiment of the present invention.

FIG. 18 depicts a wound exudate system containing thermal mass sensors,in accordance with an embodiment of the present invention.

FIG. 19 depicts a wound exudate system configured within a collectionchamber, in accordance with an embodiment of the present invention.

FIG. 20 depicts a graph showing different spectral intensities, inaccordance with an embodiment of the present invention.

FIG. 21 is a flow diagram, of a process for spectral analysis of woundexudate, in accordance with an embodiment of the present invention.

FIG. 22 is an exemplary two-dimensional vector map representing a rangeof wavelengths measured during spectral analysis of wound exudate, inaccordance with an embodiment of the present invention.

FIG. 23 is a spectral graph of the measurements of the map of FIG. 22,in accordance with an embodiment of the present invention.

FIG. 24 is an exemplary three-dimensional vector map representing arange of wavelengths measured during spectral analysis of wound exudate,in accordance with an embodiment of the present invention.

FIG. 25 illustrates an alternative embodiment of a wound exudate systemdisposed within an ancillary collection chamber, in accordance with anembodiment of the present invention.

FIG. 26 is a flow diagram illustrating an exemplary process forobtaining flow measurements of wound exudate measurements, in accordancewith an embodiment of the present invention.

FIG. 27 is a two-dimensional graph depicting flow rate measurements, inaccordance with an embodiment of the present invention.

FIG. 28 is a flow diagram illustrating the steps in a read and assessloop process, in accordance with an embodiment of the present invention.

FIG. 29 is a flow diagram illustrating a process for obtaining readingsof wound exudate, in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION

A system, apparatus and method for monitoring and assessing woundexudates are disclosed herein. The system and apparatus (“wound exudatesystem” or “system”) allow for convenient assessment of wound exudatesfrom a wound site and may provide real time quantitative and predictivefunctionality, as well as an integrated inline diagnostic solution.Also, the system may be integrated into a wound treatment device.

In addition, a system and method for collecting physiological data, andpredicting wound healing outcomes based on trends of values of exudateflow rate and other characteristics are also disclosed.

FIG. 1 is a block diagram of an embodiment of a wound exudate system 1,in accordance with the present invention. In this embodiment, sensors ordetectors 11 may detect and retrieve data representing the condition ofa wound. This wound data may be transferred electronically via wired orwireless means 17 to one or more processors 15. The processors may,among other things, predict wound state and other treatment solutions,based on the wound data.

Optionally, data may be stored in a memory 16. Information from theprocessor(s) 15 may be transmitted to an output device 19 by any meansknown in the art, in order to inform or alert a user about the health orstate of a wound.

FIG. 2 depicts one embodiment of a wound exudate system 18. Inaccordance with an aspect of the present invention, the system 18 isgenerally in fluid communication with a wound 3 (and wound exudate) of apatient 5. Fluid communication between the system 18, and the wound 3,may be by any means known in the art, e.g., a wound drain 7 that is partof a wound therapy device 9.

The wound exudate system 18 may include one or more sensors or detectors11, which may be used to detect various parameters, including but notlimited to temperature, pH, color, viscosity and tone. These parametersare useful indicators of present wound state, and may be used inaccordance with aspects of the present invention to render viabletreatment options.

The wound exudate system may optionally employ one or more types oflight sources 13. The light sources 13 may emit varying wavelengths oflight, depending on their programmed functionality. The wavelengths oflight may be emitted through the wound exudate and may be altereddepending on the characteristics of the exudate itself.

The wavelengths may then be detected by the sensors or detectors 11. Thewavelengths detected by the sensors or detectors 11 may representvarious conditions of the wound exudate being analyzed. The sensors ordetectors 11 may transmit information representative of the detectedwavelengths via electronic circuitry 17, to one or more processors 15integral within the wound exudate system 18.

The one or more processors 15 may be adapted to receive the detectedwavelength data, and conduct various analyses by way of programmedprocesses. The processor(s) 15 may receive the wavelength data from thesensor(s) 11, and use such data in appropriate process. A determinationof the process can be any type of diagnosis or categorization of woundhealth or healing, as well as a prescribed treatment regimen. Variousinformation including but not limited to historical data, processes, andvector maps may be stored in a memory 16.

The determination of the process may be communicated, wirelessly or viawired means, to be displayed on an onboard or external display 19. Asshown in FIG. 2, the exudate system 18 may be integrated directly intothe wound therapy device 9. In this configuration, the processor 15 maybe integrated into the wound therapy device, and the sensors, detectorsand circuitry may be integral with a wound drain that is part of anactive treatment device, or a bandage or dressing.

The system 18 may detect the presence of blood in the exudates, as wellas monitor and assess other physiological values relevant to woundexudates, such as flow rate/quantity, color, bacterial traces,temperature, pH and the like.

FIG. 3 is a flow diagram illustrating an exemplary wound exudate systemprocess 500. The blocks in FIG. 3 are representative of variousfunctions of a wound exudate system, which may be combined, omitted,added, or reordered as suitable.

In block S501, sensors detect and/or measure one or more parameters ofthe wound exudate. Measurement Data obtained in block S501 istransmitted to and received by one or more processors in block S503. Theprocessors then analyze the received data in block S505. Based onresults of analyzing, determination (s) may be made in block S507regarding the measurements by the sensors. Those determinations, whichmay include a diagnosis or treatment guideline may then be outputted viaan alarm or warning in block S509, or an output display in block S510.

Integrated Structure

The wound exudates systems disclosed herein and illustrated in theattached drawings may contain various structural features. The systemmay be configured differently to attach to an existing wound therapydevice, or be integrated directly into one of these devices. Thestructure of the system may also include sources of light for spectralanalysis, as well as sensors or detectors for detecting the lightemitted by these light sources. Detection of light at a particularwavelength after it has been emitted through wound exudate may indicatethe value of a certain parameter of the exudate. The system may alsoinclude sensors for measuring non-spectral parameters such astemperature and pressure.

FIG. 4 depicts an embodiment of a wound exudate system 28 integratedinto an existing wound drain line. The system contains a light source 29for emitting light of a certain wavelength(s) into the exudate. Thesystem also contains a detector 30 for detecting and/or sensing theemitted wavelengths of light after it has passed through wound exudate.Amplitude of the detected wavelengths represent the spectral attributesof the exudates and may be indicative of wound state.

Additionally, the embodiment depicted by FIG. 4 depicts an opticalbarrier 31 disposed on the exterior of a wound drainage line 32. Theoptical barrier 31 is useful for avoiding ambient light from reachingthe wound exudate. This increases the accuracy of the detection, as itavoids any artifacts that may be caused by light other than that emittedby the source 29.

FIG. 5 depicts another alternative embodiment of the present invention,in which the system may contain multiband sources of light, including anarrowband source 33 and a broadband source 34. Multiple multibanddetectors 35 may also be disposed within the system. Multiband sourcesand detectors may be useful for detecting various wavelengths of lightand therefore different attributes of the exudates. The detectors 35 maybe configured to remove unwanted ambient light and obtain more completespectral information.

In another embodiment, which may be suitable for use in hospitalsetting, an exudates system may be integrated within a central suctionsystem. In this case, the exudates system may be associated and operatedin tandem with an existing central suction system, so as to warn andshutdown flow from the wound site in the case of an adverse event. Inthis case, the exudates system may clamp the wound drainage line in thecase of an adverse event. Such an embodiment may provide a safe and lowcost alternative to existing NPWT devices in a hospital setting. Thismechanism may be useful in preventing inadvertent hemorrhagic crisescreated by undetected bleeding. In this case, the central suction unitmay be pre-configured with an integrated wound monitoring

FIG. 6 depicts an alternative embodiment of a wound exudate system thatcontains a flow disruption element 41 in combination with one or moredetectors 40 and 42 and a source 44. The arrangement of the presentembodiment may provide more accurate sensing, based on the deflection ofthe flow disruption element.

In one embodiment, an exudates system may comprise a fluid channelthrough which exudates may pass. In this case, the fluid channel mayfurther comprise an obstruction located in the path of the exudates, asseen in FIG. 6. As exudates pass the obstruction, a disturbance in theflow is created. The behavior of the flow in and around the disturbancemay be useful for measuring parameters of the flow, such as viscosity,concentration and/or composition of solid matter, etc. The disturbancein the flow can also be used to better mix the exudate, which may beuseful for improving measurement accuracy. Any signal variation betweendetectors 40 and 42 may be related to the flow disruption element.Viscosity may also be used to determine general water content of theexudates, as well as the presence of large molecules.

A wound exudate system may also be configured with a flow drain arrangedin a tortuous path 60, as seen in FIG. 8. This configuration mayfunction to eliminate ambient light from the sensory region 59.

In another embodiment of the present invention, an exudate assessmentsystem may also have structures and shaped tubes in the flow path toensure that the fluid under analysis does not mix with previouslycollected exudates prior to being assessed, as seen in FIGS. 8, 19 and25.

In yet another embodiment, the exudates system may have a chamber ortrap 98, as seen in FIG. 19, into which fluids can pool, or low so as toassist with obtaining more precise measurements regarding the physicalstate of the exudates. Measurements, such as flow rate may be taken ofthe pooled fluid, the flowing fluid, or both. This embodiment may beparticularly useful for measuring the thermal mass of the exudate.

The exudates system may also comprise a compartment to be filled byexudates leaving the wound site as seen in FIG. 19. In this embodiment,the compartment may be suitable for isolating exudates for analysis orto periodically weigh exudates removed from the wound site so as toassess the rate of fluid removed from the wound site over time. Thecompartment may include an automatic means for emptying when the fluidvolume reaches a set level. Alternatively, the Compartment may have anactive system such as valves, to empty the compartment when the fluidreaches a set level.

In this embodiment, the exudates system may comprise one or more valvesto direct and/or interrupt flow through the wound drain. In yet anotherembodiment, the exudates system may draw off fluid for a sample withoutfully interrupting flow through the fluid line. The separated fluid asindicated in FIG. 19, is analyzed within the line and allowed to remixfurther downstream. An alternative design may include a sampling portfor caking a sample for analysis.

In an alternative embodiment, the exudates system may be integratedalong an inner or outer surface of a canister or arranged, so as to matewith a canister. In this embodiment, the system may be arranged todetect the values of various physiological parameters of the exudatesaccumulated during use. In this case, the system may monitor and detectthe weight, height, impedance, etc. of the exudates as it accumulates inthe canister. Such information may be valuable for determining if anadverse event has occurred, such as the onset of bleeding. It may alsobe valuable for determining the overall rate of exudates removal fromthe wound site, thus providing predictive planning for canister changes,or even to assess wound progression from a highly exudating state to asuperficially exudating state.

Changes in the rate of exudates flowing from the wound site may beindicative of a change in the wound state. In another instance, changesin the composition of the wound exudates may indicate a clinicallyrelevant change in the wound state. Such changes in exudates removalrates may also be useful in determining how to most optimally changefrom one therapy to another. In one instance, a relative change from ahighly exudating wound to one of a superficially exudating wound may beuseful to monitor. A transition from a highly exudating wound to asuperficially exudating wound may provide useful information as to whena patient may be transferred from a more expensive to a less expensivetherapy. An example of an expensive therapy is NPWT, while examples oflower cost therapies are moist wound dressings or bandages.

The exudates system may comprise a sensor or series of sensors suitablefor determining the values of the above properties of wound exudates.

The exudates system may also comprise one or more disposable sensors forenabling contact based measurements of the exudates. Such sensorelements may comprise acoustic, photoacoustic, electrochemical, optical,and/or impedance spectroscopic elements arranged so as to monitor valuesof one or more parameters of the exudates.

The sensor or sensors may be arranged so as to collect informationthrough the outer film of a dressing or through the wall of a wounddrainage line. The sensors may be temperature sensors, optical sensors,impedance sensor, electrochemical sensors (e.g.,: amperometric sensors),capacitive sensors, or the like.

The exudates system may comprise any type of flow sensor known in theart for determining the quantity or rate of fluid removed from a woundsite. The flow sensor may be of a contact or non-contact type. In thecase of a non-contact type flow sensor, the sensor may be a levelsensor, a load cell, a flow event timer, a droplet counter, avelocimeter or the like. In the case of a contact type flow sensor, thesensor may be a load cell, pressure head monitor (such as a manometer),a strain gauge, a turbine, a thermal mass sensor, pressure lossmonitors, a tow line, or similar.

Any physiological parameter of wound exudates can be assessed usingembodiments of the present invention. Particular parameters of interestmay include, flow of wound exudates, volume rate, pH, temperature,hemoglobin concentration, color and tone.

In one embodiment, the exudates system may evaluate exudates flow ratesby measuring the rate at which a collection chamber fills, as seen forexample in FIGS. 19 and 25. In one embodiment the exudates system maycomprise a combination of a load cell with a measurement chamber tomeasure flow rate and an accelerometer to monitor orientation of themeasurement chamber with respect to the vertical axis, as seen in FIG.19. Combined signals from the sensors may be used to determine thecorrect flow rate of exudates from the wound site independent of theorientation of the exudates system.

In yet another embodiment, the exudates system may have a chamber ortrap 98, as seen in FIG. 19, into which fluids 97 may pool, or flow soas to assist with obtaining more precise measurements regarding thephysical state of the exudates. Measurements, such as flow rate may betaken of the pooled fluid, the flowing fluid, or both by sensors 101.This embodiment may be particularly useful for measuring the thermalmass of the exudate.

The exudates system may also comprise a compartment 98 to be filled byexudates leaving the wound site as seen in FIG. 19. In this embodiment,the compartment 98 may be suitable for isolating exudates for analysisor to periodically weigh exudates removed from the wound site so as toassess the rate of fluid removed from the wound site over time. Thecompartment may include an automatic means for emptying when the fluidvolume reaches a set level. Alternatively, the compartment may have anactive system such as valves 99, to empty the compartment 98 when thefluid 97 reaches a set level. Fluid may enter the compartment 98 throughan inflow tube 96, and exit the compartment 98, via an exit tube 103.

In this embodiment, the exudates system may comprise one or more valves99 to direct and/or interrupt flow through the wound drain. In yetanother embodiment, the exudates system may draw off fluid for a samplewithout fully interrupting flow through the fluid line. The separatedfluid as indicated in FIG. 19, is analyzed within the line and allowedto remix further downstream. An alternative design may include asampling port for taking a sample for analysis.

Table 1 depicts various flow rates and their potential clinicalindications. By quantifying these flow rates, and assessing themtogether with the other physiological parameters discussed herein, anaccurate prediction of wound health may be obtained.

TABLE 1 Exudate Clinical Volume Wound State Relevance Nothing dry wounddesiccation Scant moist wound tissue Normal (good) Somewhat wet woundtissue Potential maceration Moderate saturated wound Likely macerationtissues Copious wound tissues are maceration bathed in fluid

Flow Rate Example

In one example of the present technology, a collection canister wasbuilt to demonstrate flow measurement using the concept illustrated bythe embodiment in FIG. 25. FIG. 25 is an alternative embodiment of thepresent invention depicting a wound exudate system and strain gaugesdisposed within an ancillary collection chamber. Such measurements maybe taken by one or more sensors, including but not limited to straingauges 236, a capacitive level gauge 244, optical gauge elements 242,and electrical gauge elements 240. Standard types of gauges formeasuring weight or level are well known in the art. For example astrain gauge is based on a simple electrical circuit, wherein mechanicalstress caused by change in weight causes the electrical resistance ofthe elements to change in proportion to the weight applied. Acapacitance gauge reads a different level of capacitance between twopoints. In the present technology, the level of fluid 237 in the chamber(e.g., the wound fluid) may have a different value of capacitance tothat of air so the level of the fluid in the container may bedetermined. Alternatively, an optical gauge may use light to determinethe distance between two points (e.g., the top of the canister and thefluid may indicate changes in the level of the fluid 237.

The system in this particular example may include a small reservoir 230in fluid communication with a larger reservoir 232, an inlet port 234feeding into the small reservoir 230. The small reservoir 230 wasattached to the larger reservoir 232 with a flexible support 238. Astrain gauge based load cell 236 was applied to the flexible support inorder to measure flexure of the support during use 238. Saline was usedto approximate the fluid under measurement during the study. The systemwas also equipped with electrical gauge elements 240, optical gaugeelements 242, a capacitive level gauge 244. Therefore, the exampledemonstrates that individually, or if necessary in combination,different sensor types may be used to determine flow rate.

In this example, small amounts of fluid were fed through the inlet andthe sensor response was recorded on a computer (PC). During injection offluid, the reservoir was subjected to chaotic disturbances in an attemptto disrupt the sensor readings. Such inputs would be typical ofmovements experienced by the device during a mobile use scenario. Theresponse data was filtered using finite impulse response and infiniteimpulse response filters. The filters were used to remove movementartifacts and recover a usable signal from the input.

In general, the signal detected the system was related to the weight ofthe small reservoir. This is in turn related to the time integral of theflow rate of fluid into the container. Thus the flow rate was able to beextracted from the reservoir weight signal.

A valve 246 was used between the small reservoir and the large reservoirin order to drain and reset the reservoir when it became too full. Theflow dynamics of this emptying process can be used to determineviscosity related information about the fluid under study.

FIG. 26 depicts a process 260 that is further related to flowmeasurement of FIG. 19 and FIG. 25. The process 260 includes (1) takinga flow reading in block S251; (2) removing any movement artifacts inblock S252 (1); and (3) calculating a flow rate in block S253 based onmethods known in the art and, in particular, those disclosed herein. Ifthe calculated flow rate is acceptable, measurements will continue to betaken. If the flow rate is not acceptable an alarm or alert is triggeredin block S254. The flow rates calculated in process 260 can also bemapped in a graph as seen FIG. 27. As with process 260, the spectralmaps described here in various values along the flow rate map mayindicate an onset of infection and/or bleeding, i.e., 262.

Exudate flow rate, which may be measured by the methods describedherein, or any of the methods known to those of ordinary skill in theart is a reliable predictor of wound health. In certain embodiments ofthe present invention, flow rate values, and changes in flow rate valuesmay be detected through various means and may also be useful indetermining how to most optimally change from one therapy to another. Inone instance, a relative change from a highly exudating wound to one ofa superficially exudating wound may be useful to monitor. A transitionfrom a highly exudating wound to a superficially exudating wound mayprovide useful information as to when a patient can be transferred froma more expensive to a less expensive therapy. An example of an expensivetherapy is NPWT, while an example of a lower cost therapy is moist wounddressings or bandages. In one instance, changes in the rate of exudatesflowing from the wound site may be indicative of a change in the woundstate. In another instance, changes in the composition of the woundexudates may indicate a clinically relevant change in the wound state.

In another embodiment, color assessment of a disposable element withinthe device, or disposable electrodes within tube maybe possible. It mayalso be possible to map color profiles of exudates to pH. Severalfluorescent nanoparticles systems can change color based on pH. Inaddition, a conjugated polymer could be used to do the same (redoxpotentials will change based on the pH of the local environment).

Additionally, it is possible to have a color changing element in contactwith the exudates that is responsive to local pH changes and a reusablereader element that can analyze the pH changes via monitoring colorresponse of the color changing element.

Temperature is useful for assessing bleeding events as well as tomonitor for infection. Core blood is generally warmer than theinterstitial fluids in the dermis. In general, embodiments using adisposable metallic element for measuring temperature values, as well asembodiments with reusable probes are envisaged.

In one aspect of the present invention, near infraredspectroscopy/visible spectroscopy may be used to detect the values ofoxygen in hemoglobin present in wound exudates. The presence of oxygenmay indicate the presence of hemoglobin, and therefore blood. In aspectsof the present invention this could trigger an indicator, or cause oneof the pinch mechanisms described herein to clamp a wound drain line toprevent further bleeding. In yet other embodiments, this event wouldprovide a caregiver with appropriate treatment guidelines.

Tone and/or luminocity may be used to describe the color of theexudates. Changes in tone and/or luminocity may be indicative of changesin the physiological state of a wound and its stage of healing. Aquantification system for evaluating the wideband absorption spectrummay also be useful for assessing the color and tone of the exudate.

In one embodiment, a wound system may include one or more laser diodesthat provide very narrow wavelengths used to perform measurements. Inthis case a spectral map and/or vector can be generated by using asingle detector in combination with multiple laser diodes and/or one ormore scanning laser diodes. A scanning laser diode can produce amodulated wavelength through modulation of the driving signals producedby the drive electronics. Such modulation makes for simplified removalof artifacts caused by ambient light interference, movement and thelike.

A method for quantitative, real time spectral detection and assessmentmay be a steady, pulsed or modulated near infrared spectroscopy orfunctional near infrared spectroscopy technique. It may use multiplewavelength spectroscopy and the like. In one case, a exudates system mayinclude a color analysis system in combination with a white lightsource. A color analysis system may comprise one or more photodiodes incombination with one or more bandpass filters in order to provideseparate responses for segments of the light spectrum. One or moreoutputs from each band are generated, with each output providing thespectral component of a vector. Output vectors can be mapped to exudatesstates, thereby creating vector maps useful for determining the state ofthe exudates and thus, statements about the physiological condition ofthe wound, as seen in FIGS. 22-24.

FIG. 20 is one example of an absorption map or tone map for analyzingdifferent absorption wavelengths. As depicted in FIG. 20, byrepresentative example only, a two-dimensional map shows absorption of asource spectrum 108 along a blue 104, yellow 105, red 106, and NIR 107wavelength. This particular example depicts broadband detection for thecolors indicated. However, alternative embodiments, a single broadbanddetector could also be used. Particular values seen in an absorption mapcan be translated into a particular assessment of a wound state. By wayof example only, a process performed by the processor may be encoded tosignal an alarm or pinch a drain line if a particular tonal colorreaches a certain level.

FIG. 21 depicts a flow diagram of various operations performed to assessthe color or tonal characteristics of a wound exudate. An initial blockS110 may obtain various spectral components. Next, any ambient light maybe removed in block S112 to increase the accuracy of any spectralreadings from the wound exudate. Once block S112 is completed, tonevectors are calculated in block S114 from the readings obtained fromblock S110. Tone vectors may be calculated by any means known in theart. However, in preferred embodiments, the vectors may be calculatedusing the following equation:

$\begin{matrix}{\delta = {\sum\limits_{i = 1}^{N}\; {A_{i}\chi^{i}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Equation 1 is a linear weighting equation that casts portions of thesensor spectrum (each portion indicated by a coordinate X^(i)) into annth order vector space. Each portion of the spectrum is weighted by ascalar weighting parameter A_(i) (in this example only, more generallythe weighting parameters may be equations, or algorithms that better mapresponses into the vector space, adjust for subject parameters, as wellas adjust for changes in ambient conditions).

The relationship computed in the equation may be used to map readingsfrom individual sensors, wavelengths, and/or spectral bands into the nthdimensional figures, as disclosed herein. This process may be done toessentially create a map of the input responses into a quantifiablespace such that diagnostic information may be more readily extractedfrom the collection of input signals. So for example, delta maps intothis Nth order space, regions of which may have statisticallysignificant relationships to various disease states, contraindicationsfor the existing therapy, etc. By correlating where patient data fallson the map, and examining the historical data and trending data, thetechnology can assist in decision making with regards to therapeuticdecisions.

These tone vectors are then compared to a tone map block S116 containingstandard or acceptable tonal values. In assessing for any potentialproblems block S118, the tone vectors from block S114 are compared tothe accepted values in block S116. If any of those values fall short ofor exceed the acceptable ranges from block S116, a predetermined actionin block S120 is performed. A programmed action may include, triggeringan audible alarm from actuating one of the latch mechanisms describedherein.

In particular, luminocity and tone may be indicative of infection,bleeding or increased edema in a wound, all conditions requiring urgentattention. Certain embodiments of the present invention may compare andanalyze detected tone and luminocity values with predetermined values oftone and luminocity to provide a patient or caregiver with valuabletreatment guidelines (see FIGS. 22, 23, and 24). Values of these variousparameters may be combined into vector maps.

FIG. 22 is a two-dimensional vector map 200 based on a range of colorsat a given luminocity 201, measured from the wound exudate. Map 200represents data points along the spectral graph 206, as shown in FIG.23. Different locations on the vector map 200 may indicate thelikelihood or actual occurrence of various events related to woundstate. For example at location 202 a normal exudate trend may beindicated, while locations 203 and 204 may indicate suspected bleedingor a high probability of bleeding, respectively. Location 205 mayindicate the presence of an actual bleeding event. Graph 206 in FIG. 23represents a line graph of three individual spectral profiles over agiven period of time.

FIG. 24 is a three-dimensional vector map, similar to thetwo-dimensional map shown in FIG. 22, which is based on a range ofcolors measured from the wound exudate. Spectral components of woundexudate translated into vectors, may be mapped in such a two orthree-dimensional map. By increasing the number of color channels, andtherefore the number of wavelengths able to be detected, the sensitivityand accuracy of the system can be improved. Various points along thevector map, whether two or three-dimensional, may also indicate a trendof wound health. For example curve 220 may indicate an initial trendwhile curve 222 may indicate a slight progression towards infection.Curve 224 may indicate the actual onset of infection while curve 226 mayindicate various regions with a probability of infection.

Given points, (e.g., 227 and 228) in the vector map may indicate acertain wound state. Such a wound state may correspond to a prescribedtreatment guideline. These treatment guidelines may include, but are notlimited to varying the settings of an NPWT, or closing off a wounddrain. Presence of bacteria or other infection may necessitateadministration of antibiotics to the patient.

Qualitative analysis of the color spectrum of wound exudates may beanother valuable tool for assessing wound health. Table 2 depictsvarious exudates, their color, transparency and possible clinicalindications.

TABLE 2 Type of Color, Exudate Transparency Viscosity IndicationsSerous- clear, straw low normal (good) transudate colored, viscosity,watery Fibrinous cloudy low contains fibrin viscosity, strands Sero-clear, pink low normal (good) sanguinous viscosity, watery Sanguinousred low blood vessel viscosity trauma and watery Sero-purulent murkyyellow high infection to creamy viscosity coffee Purulent yellow, grey,high presence of green viscosity inflammatory cells, infection, pyogenicorganisms Hemo-purulent Dark, red, high established viscosity infection,and sticky presence of neutrophils, bacteria, inflammatory cells withblood leakage due to vessel damage Hemorrhagic Red thick infection withtrauma

Practically, when considering diagnostic and treatment options for apatient suffering from a wound, in general, a clinician does not want toJoe inundated with data. It is desirable that an exudate assessmentsystem analyze values detected from a wound, and provide decisionsupport for the user regarding treatment options, rather than just datapresentation. To that end, the system of the present invention iscapable of analyzing the values of the data obtained from the sensorsand/or detectors. Once an analysis is conducted the system may providean assessment of the wound, as well as treatment guidelines.

Embodiments of methods and apparatuses according to the presentinvention may detect values of various parameters in real time, andperform analyzing processes as shown in FIGS. 28 and 29. These analyzingprocesses provide not only real time detection, which gives a much moreaccurate and reliable assessment of the wound, but also gives real timetreatment suggestions, as they evaluate the current state of a wound,and not exudate that has been sitting in a collection canister for anextended period of time.

The exudates system may comprise processing components to performvarious processes that provide or output a wound state condition ortreatment option, which may include, among other things, microelectroniccircuits such as discrete circuits, microcontrollers, microprocessors,ASICs, FPGAs or the like, to condition and analyze sensor data tomeaningfully interpret the physiological parameters of the exudates. Theprocessing components may be located integrally within the system sothat the sensors, light sources and processing components are allcontained within the same device. In an alternative embodiment, theprocessing components may be remotely located from the other parts ofthe system.

The process performed for analysis are generally adaptive and may bebased on, one or more of the following: an averaged one-dependenceestimators (AODE), Kalman filters, Markov models, back propagationartificial neural networks, Baysian networks, basis functions, supportvector machines, k-nearest neighbors algorithms, case-based reasoning,decision trees, Gaussian process regression, information fuzzy networks,regression analysis, self-organizing maps, logistic regression, timeseries models such as autoregression models, moving average models,autoregressive integrated moving average models, classification andregression trees, multivariate adaptive regression splines. The sensordata may be analyzed from multiple sources using sensor fusionapproaches. The specific process may be evolved using supervisedlearning, unsupervised learning, and/or reinforcement learningapproaches. In addition, the device may comprise associated powersources and the like to drive the onboard electronics (sensors,microelectronic circuits, communication elements).

When tone and luminocity values are analyzed in combination withtemperature readings, flow rate and NIR readings, a comprehensivestatement may be made about the actual state of the exudates. Byapplying the processes described above to the various physiologicalparameters, including tone, luminocity, temperature and flow, aclinically appropriate set of treatment guidelines may be delivered bythe system, thus eliminating the need for the caregiver or patient tohave to interpret large amounts of data and make a subjectivedetermination.

FIG. 28 is a flow diagram of an exemplary process to obtain and analyzeparameter readings, as well as present and display warnings andtreatment options.

The process of FIG. 28 is also referred to as a read and assess loop.The wound monitoring system may be at a sleep state to reserve or reducepower consumption. The system may be “woken up” during a wake-up phaseS201, in response to some input. This input may be any type of stimulisuch as motion, or as a result of a timer. Once awake, the system willobtain parameter readings S203. After block S203, the device mayimmediately return to a rest state in block S222. If this is the logicpath followed by the device, the readings obtained in block S203 mayalso be stored in a memory.

If after obtaining readings in block S203, the system does notimmediately return to rest 3222, the device may be conditioned andcleaned in block S205 In the first mode from wake up, the device may bein a loop where it simply wakes up takes a reading, potentially storesit and then rests, as already described. If instead of resetting, thedevice needs to switch modes to monitoring disturbances from block 207it will need to activate a conditioning function, which may be there toobtain the raw signals from 207 and prepare them for analysis (e.g.,converting from analog to digital signals depending on sensor type orother forms of data conversion/signal conditioning know in the art). Itmay also be necessary to clean the signals because many signals can have“noise” or spurious data which may need to be filtered out beforeprocessing in 209.

If after obtaining readings in block S203, the system does notimmediately return to rest S222, the device may be conditioned andcleaned in block S205. This cleaning step aids in obtaining an accuratereading and filtering out any extraneous data or artifacts. After blocksS205 the readings obtained in block S203 are converted to vectors andassigned a corresponding weight S209. The weighting of the variousreadings can be based on any factor known in the art. By way ofrepresentative example only, one parameter such as temperature may begiven a higher weight than pH, or vice versa. Such weighting can bechanged from patient to patient or as applied to the same patient. Suchweighting may also be assigned based on historical weights of variousparameters. Once the readings are vectorized and weighted, the processorin block S213 compares the vectorized and weighted values to a vectormap. At this point, the processor analyzes the data, and makes adetermination, based on the vector's location on a vector map, as towhether the value is in a safe region in block S217. What constitutes asafe region is also a parameter that may be predetermined and stored ina memory associated with the processor. If, it is determined in blockS217A the readings are in a safe region but appear to be trending towardan unsafe region, the weights of those readings may be adjusted in blockS217(b) to assign a higher priority to said values. Next, based on theadjusted weights, the system makes a determination as to whether or notit is worth warning a user S217 (c) of the trend toward an unsaferegion. If based on predetermined values, the processor determines thatit is in fact worth warning a user, then a warning is issued in blockS217(d). If not, the system returns to the rest state in block S222 forpower minimizing consumption.

If the vectorized, and weighted reading is not in a safe region, theprocessor determines whether or not the unsafe reading is a newoccurrence in block S219. If it is a new occurrence, the alert weight ofthe occurrence is increased in block S220. Once the alert weight isincreased, the processor returns to the rest state S222. If the deviceor processor determines that the unsafe reading is not a new occurrence,a determination is made as to whether the alert weight is critical inblock S219(b).

If the alert weight is not critical, then the alert weight is merelyincreased in block S220 and the device returns to rest state S222. Ifthe alert weight is critical, the processor determines in block S219(c)which region of the vector map the value falls in and what type ofcondition is therefore indicated by the value of the readings. Based onthe region and type of event detected at in block S219(c), an action isinitiated in block S219 (d). An action may be an alert, an alarm, apinching of a wound drain, or any other type of event or warning, whichaids the user in assessing or treating the wound. If the action taken atblock S219(d) is resolved, as determined in block S219(e) the deviceand/or processor will record the event in block S219(f) and return torest S222. If the event has not been resolved, the action at blockS219(d) will be repeated or sustained.

At block S203 at the read and assess loop, readings are obtained. FIG.29 is a detailed logic diagram of operations performed in block S203.Once the processor or device “wakes up,” the sensors 301 are thenpowered up. Once the sensors are powered up, parameter values may beobtained S303. As depicted in FIG. 29, parameters such as spectralcontent of the wound exudate S303(a), flow S303(b), temperature S303(c),biomarker detection S303(d), and viscosity (e) are detected andmeasured. While these parameters are illustrated in FIG. 29, they are byway of representative example only and the current invention can be usedto measure any parameter present in wound exudate. These values are thenconverted to digital signals in block S305, which may be done as a lowpower conversion to reduce power requirements. Once the values nave beendigitized, the processor in block S309 performs a check for values thatmay be statistical outliers.

At block S309, as part of the outlier analysis, the values may be storedin a memory to be incorporated into the historical data S309 (a). If thesample is determined to be a good sample in block S311, the processorwill perform a specific calibration S313 to adjust to the specificpresent conditions. Once this adjustment is performed, the processor inblock S315 may perform the conditioning and cleaning similarly as instep S207. If the sample is determined by the processor in blocks to notbe a good sample, the event is recorded in block S311(a). If the badsample is a recurring problem, which may be detected by prior historicalvalues, an error message is displayed to the user in block 311(c). Ifthe problem sample is not recurring, the processor returns to restS311(d).

After the processor has determined the wound state and/or treatmentinformation, that data may be provided or communicated to a user orpatient. As discussed above, the system is capable of communicating orproviding values and treatment guidelines to a user. In addition, thesystem is also capable of communication directly with a negativepressure wound therapy device in order to effectuate necessary changes.

The system comprises means for alerting a patient or caregiver to thepresence of an abnormal state, quantity, or condition of the exudates.In this case, it may comprise one or more lights, a display, a speaker,a vibrating element, or similar in order to communicate information to apatient or caregiver.

The device may further include wireless communication capabilities so asto deliver relevant information about the wound exudates to the NPWTdevice. Such information may include the presence of blood in theexudates, the presence of bacteria, a change in the absorption spectrumof the exudates, a change in the flow race of the exudates, and thelike.

Results of the wound assessment may be displayed through any type ofgraphical user interface, monitor or other type of display. Results ofwound assessment may also be conveyed to a clinician and/or patient bythe use of indicators as seen. Indicators may be any visual indicatorssuch as lights, or audible indicators such as buzzers or alarms, or ahaptic communication device such as a vibration motor to alert theclinician or patient when a particular event has been detected.

The exudates system may comprise a means for communicating via a networksuch a cellular network, a wireless personal area network (WPAN), widearea network (WAN), metropolitan area network (MAN), local area network(LAN), campus area network (CAN), virtual private network (VPN),internet, intranet or near-me area network (NAN).

The exudates system may be arranged as a node in a network, thusproviding an element in a ring, mesh star, fully connected, line, treeor bus network topology. In one embodiment the exudates systemcommunicates relevant values and as a node in a mesh or star networktopology.

The exudates system may comprise means for interfacing with a localtelecommunications network, such as a cellular network via a locallypositioned mobile handset, a wireless node, a wireless modem, phoneadaptor or the like.

The exudates system may communicate relevant information through thenetwork using various protocols such as IrDA, Bluetooth, UWB, Z-WAVE,ANT, or ZigBee. Preferably, the relevant information is sent via lowpower protocols such as Blue tooth low energy, ANT or ZigBee.

The exudates system may comprise an integrated power switch such thatpower is automatically provided to the onboard microcircuitry as soon asthe system, or a wound device with which the system is associated, ispositioned so as to effectively assess exudates. In another embodiment,the system may comprise a proximity sensor to awaken the system itselfor wound device from sleep. The sleep function may be useful to reservepower during periods of nonuse.

In another embodiment, the system may include a wound dressing withfluorescent biomarkers as shown in FIG. 7. Biomarkers 50 may be employedfor detecting various conditions. Biomarkers 50 can be assessed byexternally positioned optical sensors 52, thus providing a non-contactway to assess exudates properties. The optical sensors 52 can usecolorimetric analyses to read the biomarkers 50 and detect the presence,absence or quantity of a particular value of a physiological parameter.In one embodiment, an optional light source 56 may be used to emit lightinto the wound exudate.

In this particular embodiment, optical sensors 52 may be located on theouter surface of an opaque, or optically transparent tube 54. Biomarkerscan change based on local pH, local impedance, local redox potentials,color, and can fluoresce based on certain criteria, all of which areknown in the art. As they interact with the exudates they are useful todetect the presence or absence of certain biological materials. Theexudates system may read, detect or assess the biomarkers throughoptical means (color change, fluorescence, etc.), or electrical means(pH, redox, impedance, etc.).

In yet another embodiment, the system may detect presence of aninfection, including but not limited to methicillin resistantstaphylococcus aureus (MRSA) or vancomycin resistant enterococci (VRE),to alert a patient at home that they need in-patient hospital treatment.These various infections may be detected by assessing biomarkersintegrated within the system, or by assessing the value of otherphysiological parameters, including but not limited to temperature.

In one preferred embodiment, each process performed by the system can bedone in a non-contact fashion such that the sensors and electronicssupporting the sensors do not come into contact with the exudates. Thisallows the components of the system to be reused, as cross contaminationis avoided, thus sparing the expense of having to use replaceablesensors with each use.

Non-contact is defined herein as not having direct contact between thefluid under analysis, and the sensory elements. Thin membranes in thedrainage lines can be used to sense pressure, temperature, etc. (seeFIG. 17). FIG. 18 depicts an alternative embodiment, of a wound exudatesystem, which contains pressure sensors. In the present embodiment, thewound exudate system may contain two sections adjacent to a wound drain89. Those two regions are indicated in FIG. 17 as 91 and 92 at theinterface of the system and the drain where the wall thickness of thesystem is reduced. At the precise interface between the system and thewound drain, a thin membrane is disposed thereon (not shown). Thethinner membrane allows pressure sensors to detect a pressure inside thedrain at locations 91 a and 92 a. A pressure P₁ is assigned to apressure reading at location 91 a and a second pressure P₂ is obtainedfor the pressure reading at location 92 a. The difference between thesetwo pressure readings can be used to establish, for example, flow rate,viscosity. The configuration described above may be self-containedwithin a disposable shunt for placement over an existing wound drainline, or designed as an integral component of a wound drain line.

FIG. 18 depicts an embodiment similar to that as seen in FIG. 17.However, the embodiment depicted in FIG. 18 measures thermal massvis-à-vis a microheating element disposed in each of recesses 93 and 94.This embodiment may be useful to estimate flow rates along the wall of awound drain line.

The exudates system may comprise a means for pinching off, or otherwiseclosing a wound drainage line in the event of an anomaly (such as thepresence of blood in the exudates. In this case, the device may comprisean actuator that may be deployed so as to squeeze the line during anadverse event. In another case, the actuator may be arranged such thatit is forcefully retracted during normal operation and is releasedduring an adverse event, thus clamping down onto a wound drain line andpinching off fluid flow.

FIGS. 9-16 depict various control mechanisms for controlling or stoppingthe flow of any fluid from a wound. These control mechanisms may includepinch lines to control the flow of exudates upon detection of a certainphysiological value. These pinch mechanisms may also be referred toherein as latches. Different types of latches may be activated bydifferent mechanisms. In one mechanism, the latch is an active materialelement that will change shape in response to a stimulus. Suitableactive materials include shape memory alloys, electroactive polymers,piezoceramics, etc. In this particular embodiment, the active materiallatch is designed such that it releases upon stimulation.

If used as part of an NPWT system in response to a certain parametervalue, the system may pinch the wound drainage line so as to force afault (blocked line fault) on the NPWT device. In this case, the systemneed not have its own means for alerting the patient or caregiver of anadverse event, but rather may trigger an alarm that is present inexisting NPWT devices to achieve this goal.

In another embodiment, a suitable latch is designed with an integratedresistive heating element 80, a reed 81 and a disbondable fastenedregion 83, as seen in FIG. 15. The reed is deformed during manufacturingand bonded with the disbondable fastened region 83 in the deformedstate. The reed is also bonded to an attachment point 84, in which thebond is not broken. The latch system is designed such that fluid canflow through an adjacent channel when the reed is held to thedisbondable region, but that fluid flow through the channel on fluidline 85 may be blocked when the reed is released 87. Upon heating of theheating element 80, the disbondable fastened region 83 melts, deforms,or vaporizes, causing the deformed reed to break away from the fastenedregion 83. During this process, the reed bridges the fluid line 85, asshown in FIG. 16, preventing flow and optionally triggering a blockagealarm. Other alternative latch designs will be evident to someoneskilled in the art.

The wound drain may have a particular shape so as to maintain laminarflow of the exudate during suction, in addition to providing for anactuating means for pinching off a wound drain line in the event of anadverse event such as bleeding. Representative examples of thisembodiment can be seen in FIGS. 9 and 10. The mechanical elementspresent in this embodiment are comprised of a solenoid based pinch valve65. As with traditional solenoid based apparatuses, the pinched valve 65of the present embodiment contains a coil magnet 66 and a coiledactuator magnet 67. In the present embodiment, the pinched valve may beactuated to close or substantially narrow the interior wall of the wounddrain 69.

This change of the channel width of the wound drain assists in detectinglaminar to turbulent flow and may restrict flow for better analysis ormeasurement. The embodiment depicted in FIG. 9 may be combined with anyof the other embodiments described herein, such as a flow disruptionelement 70 as shown in FIG. 10. When flow disruption element is present,analysis and detection may take place along an analysis flow region 64by sources 62 and detectors 63.

As seen in FIG. 11, more than one solenoid 71 actuator can be used toenhance the pinching affect. FIG. 12 depicts an alternative embodimentwherein multiple pinching actuators 73 are disposed on opposite sides ofa wound drain line. The actuators 73, depicted in FIG. 12 can beactivated in response to a stimulus, such as the presence of blood. Inthe event the actuators 73 are activated and pinch the drain line toprevent further bleeding. An alarm 74 can signal a blocked flow line.

FIG. 13 depicts yet another embodiment of the present inventioncontaining a spring loaded, resettable latch. Upon actuation, the springloaded latch releases and causes the mechanism to pinch the wound drainline 79 in the event of the detection of some unwanted occurrence, suchas bleeding, as shown in FIG. 14. The spring loaded element 75 onceactuated can be reset and the latch 77 may be re-secured, as shown inFIG. 13. In this particular embodiment, electronics and power sourcesnecessary for operation may be contained on an external housing.

In the case of a conventional dressing or bandage, the dressingcomponent may be modified so as to easily integrate with the exudateassessment system. To enable this integration, the dressing may haveelectrical traces as an interface. The electrical traces may be printedusing electroconductive inks (Ag, AgCl, C, Ni, etc.), or formed viaseveral available RFID techniques known in the art, and embedded forelectrically Interacting with the exudate assessment system.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A system for assessing wound exudate from a wound of a patient, saidsystem comprising: a wound treatment device; detecting means fordetecting one or more values of one or more physiological parameters ofthe wound exudate; analyzing means for analyzing the values of the oneor more physiological parameters so as to obtain an assessment of thewound exudate; and providing means for providing a treatment guidelinebased on the assessment; and in which the wound treatment device, thedetecting means, the analyzing means, and the providing means areintegrated.
 2. The system of claim 1, in which the wound treatmentdevice is a negative wound pressure therapy device.
 3. The system ofclaim 2, further comprising controlling means for controlling thenegative pressure wound therapy device using the treatment guideline. 4.The system of claim 1, in which the wound treatment device is a dressingor a bandage.
 5. The system of claim 1, further comprising integratingmeans.
 6. The system of claim 5, in which the integrating means in thedressing or bandage includes an electrical trace.
 7. The system of claim1, in which the providing means is operable to transmit the treatmentguideline to an external device located remotely from the system.
 8. Thesystem of claim 1, in which the values of the one or more physiologicalparameters include luminosity values.
 9. The system of claim 1, in whichthe values of the one or more physiological parameters include tonevalues.
 10. The system of claim 1, in which the detecting means, theanalyzing means and the providing means are arranged to be isolated fromthe wound exudate.
 11. A system for assessing wound exudate from a woundof a patient, said system comprising: a wound treatment device; sensorsor detectors to detect or sense one or more values of one or morephysiological parameters of the wound exudate; a processor to analyzethe values of the one or more physiological parameters so as to obtainan assessment of the wound exudate and provide a treatment guidelinebased on the assessment; and in which the wound treatment device, thesensors or detectors, and the processor are integrated.